The invention relates to railroad car trucks or boogies, especially single axle trucks which are manufactured by National Castings Incorporated of Chicago, Ill. under the trademark UNITRUCK. These single axle trucks are mainly used on trailer carrying flat cars (TOFC) and container carrying flat cars (COFC), or on the end cars of articulated bulk load carrying railroad cars, and are rigidly secured to the structural steel framework of the bottom or under carriage of each one of the cars, closest the trackway along which the cars move. Unlike the more commonly used dual axle truck, this single axle truck has for all practical purposes, no steering capability, since its so-called passive steering is limited to about one and one-half degrees measured from either side of a horizontal axis which is normal to the longitudinal axis of a railroad car, when the car is resting on a horizontal trackway.
Current freight cars, up to about fifty feet long with truck centers of about thirty-six feet and equipped with single axle trucks of such limited passive steering, can negotiate the curves of existing trackways in the United States without derailing. However, freight cars are ever increasing, in size, some to about ninety feet, in length, to accommodate larger and heavier loads which railway companies are being asked to transport. To use existing, rigidly connected single axle trucks on such extra long freight cars would be prohibitive and cause derailment of the freight cars, since these trucks do not have the steering capability to negotiate such curves.
Thus, railroad car builders and the railway companies are faced with two alternate choices. The first choice is to use a dual axle truck at each end of these extra long freight cars, instead of the single axle truck, but this literally doubles the number of wheels, axles and associated parts required in the make up of a train of freight cars. The second choice is to use a single, dual axle truck between adjacent, extra long freight cars, but this presents a problem when freight cars are uncoupled from one another, since at least one end of an uncoupled freight car becomes unsupported for a period of time. The invention is designed to overcome such problems.
Briefly stated, the invention is in a device which is used at either end of a railroad car for supporting the car as it moves along a trackway. The device includes a single axle truck which is firmly secured to a rigid, structural steel subframe which, in turn, is rotatably mounted to the structural steel framework of the under carriage of the freight car at each end of the car. Each one of the rotatable, rigid subframes is provided with one or a pair of steering arms which are designed to engage either a single drawbar or an interlocking, rigid jaw or knuckle type coupler, both of which are used to couple adjacent freight cars together.
The steering arms are responsive to movement of the car coupling mechanism as the regular or extra long freight cars move along a curved trackway, and act to correspondingly rotate the rigid subframes to actively steer the single axle trucks along the curved trackway. Moreover, the single axle trucks of adjacent, extra long freight cars are only about ten to fourteen feet apart, as compared to about forty-six to fifty feet apart when such trucks are used adjacent each of the opposing ends of, for example, a sixty foot long railroad car, to provide further assurance that no derailments will occur, since the center distance between the trucks of adjacent railroad cars is important and effects or determines the steering characteristics of the trucks.